The invention is linked to the method for automatically adapting a reference image which is proposed in DE 10 2010 012 621.7 published after the filing date of the present application.
The particular objective here is to display an aorta of a human patient. This is advantageous in connection with the treatment of an abdominal aortic aneurysm. An abdominal aortic aneurysm is an “outpouching” on the abdominal aorta. To repair it, a so-called stent is inserted, i.e. an angioplasty. To insert such a stent, care must be taken to ensure correct placement. In order to facilitate same for the treating physician, fluoroscopic images (X-ray pictures) of the patient can be taken continuously during stent positioning. In order to avoid having to inject new contrast agent continuously into the patient, low-contrast fluoroscopic images can be taken and overlaid with a reference image which enables sufficient orientation. The reference image can be a 2D angiogram. It is advisable if, prior to treatment, a 3D image data set in respect of the aneurysm is acquired, e.g. using computed tomography angiography. Such reference data sets are sometimes pre-segmented, i.e. undergo an image processing step in which particular structures are particularly accentuated in the image. At its simplest, segmentation takes the form of extreme contrast intensification. For example, segmentation can be used to accentuate the walls of the aorta in black, while the interior of the aorta appears white.
The overlaying of the reference image with the currently captured fluoroscopic image is then performed by per se known methods for merging two images into one. For this purpose, in particular the reference systems in which the individual images were captured must be set in relation to one another by calculating a mapping rule (so-called “registration”).
To introduce a stent, guide wires and catheters are inserted into the aorta. Inserting such objects into the aorta may cause deformation of the vessel walls, particularly if the objects and instruments are very rigid. In DE 10 2010 012 621.7 it is now described that, in the event of particularly severe deformation during which the currently taken fluoroscopic images show something different from the existing reference images, these reference images themselves undergo further processing, namely to calculate how the inserted object deforms the vessel walls.
In DE 10 2010 012 621.7, deformation predictability is assumed. This predictability actually exists in the case of recurring conditions.
However, the actual conditions may be subject to significant variation: for example, in one instance a short, slightly-built male patient may be involved, another time a tall, stoutly-built female patient. Also the instruments used may be different from one another. It would therefore be desirable for the method for displaying a vessel to be able to take this variability into account in some way.